Plasma-assisted filling electron beam lithography for high throughput patterning of large area closed polygon nanostructures.

Electron-beam lithography is widely applied in nanofabrication due to its high resolution. However, it suffers from low throughput due to its patterning process. All the pixels within a pattern's boundary are needed to be scanned for patterning, which is inefficient for a large area closed polygon structure. Introducing an additional step to perform the polygon-filling function for patterning will significantly improve the fabrication throughput. In this work, we introduce a practical polygon-filling process for electron beam lithography, termed plasma-assisted filling electron beam lithography (PFEBL), that makes use of post-exposure plasma treatment on the resist which only crosslinks the top surface of the resist. Using this technique, we only need to expose the outline of the patterns during the writing process and could still obtain the full structure after post-exposure plasma treatment and development. We show that the lithography patterning efficiency could be enhanced 50 times and above while sub-10 nm resolution patterning with a sharp boundary feature size can still be obtained. The plasma exposure mechanism and development mechanism were discussed for the characteristics of the resist that enables this filling process. Our approach allows large area closed polygon structures to be patterned with high patterning efficiency, which could find uses in various applications in nanophotonic and optoelectronic devices.